Furnace and method of operating the furnace

ABSTRACT

Light metal components and/or plates are transported through a furnace in a clocked or continuous transport process and heated and optionally cooled inside the furnace by an air or gas flow. For this purpose, a continuous air-/gas circulation is generated, wherein circulating air-/gas flow flows across the light metal components and/or plates, heating and cooling them as necessary. The light metal components and/or plates entering into or exiting from the furnace perform a sealing function and prevent the air-/gas flow circulating in the furnace from escaping from the furnace.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application claims the priority of German Patent Application,Serial No. 10 2012 104 537.2, filed May 25, 2012, pursuant to 35 U.S.C.119(a)-(d), the content of which is incorporated herein by reference inits entirety as if fully set forth herein.

BACKGROUND OF THE INVENTION

The present invention relates to a furnace for the thermal treatment oflight metal component, and to a method for the thermal treatment oflight metal components.

The following discussion of related art is provided to assist the readerin understanding the advantages of the invention, and is not to beconstrued as an admission that this related art is prior art to thisinvention.

The use of sheet metal components for the production of automotivecomponents has been known for many decades. The sheet metal componentsare first formed and then combined to single modules or to an entirebody. Motor vehicle bodies are nowadays mostly formed as self-supportingbodies, so that the sheet metal components not only perform aesthetic orshaping tasks, but must also have stiffness properties to impart to thevehicle body sufficient rigidity during use.

Demands on the crash behavior are also placed on the structural vehiclecomponents, which must dissipate impact energy into deformation energythrough targeted deformation in the event of a collision.

Steel represents a preferred material due to its advantageousmanufacturability accompanied by high rigidity. In particular, thehot-forming and press hardening technology gives the steel high-strengthor even ultra-high-strength properties, so that the specific weight ofthe components could be further reduced, while simultaneously increasingthe strength values.

Today, however, not only aesthetic and safety expectations are imposedon motor vehicles, but also ecological and economic aspects foroperating the motor vehicle have become rather important. So it isespecially important that the vehicle has low fuel consumption withsimultaneously low CO₂ emissions. For this purpose, there are variousapproaches, for example the use of new drive techniques such as thehybrid drive, or a particular shape giving the motor vehicle a low airresistance.

Another approach is the use of light metal components to reduce thespecific weight of the vehicle body and thus of the entire vehicle. Inparticular, light metal components made from aluminum alloys are used.

For certain applications, for example with high degrees of deformationor when setting specific strength values in aluminum components, theplates must be thermally treated prior to forming and/or at intermediatesteps during forming and/or after forming.

Continuous furnaces known in the art include a transport system on whichsheet metal components or sheet metal plates are continuouslytransported through a furnace and heated inside the furnace. Severalapproaches exist, for example infrared heating or induction heating ofthe component or the plate inside the furnace.

However, when such furnaces are used for light metal alloys, somemethods are inefficient because the aluminum reflects, for example, theheat radiation or the methods are technically impractical, since e.g.the shaped plates or components can only be heated unevenly and thusseverely distort; more often, however, the methods are inefficient,because a large part of the input energy is not used. Anotherdisadvantage is the high space requirements of most facilities.

The furnaces can thus only be operated inefficiently, which furtherincreases the production costs of the alloy material which is anywaymore expensive compared with steel.

It would therefore be desirable and advantageous to obviate prior artshortcomings and to provide an improved furnace for thermal treatment oflight metal components, and an improved method of operating the furnacecapable of cost-effective and efficient mass production of light metalcomponents.

SUMMARY OF THE INVENTION

According to one aspect of the present invention, a furnace for thermaltreatment of light metal components which are continuously transportedthrough the furnace, includes a heat source, a conveyor transporting thelight metal components through the furnace in a transport direction, anda blower producing an airflow circulating inside the furnace. Theairflow heats the light metal components inside the furnace byconvection, and a light metal component entering the furnace and a lightmetal component exiting from the furnace are constructed as a barrier soas to hinder the airflow from escaping from the furnace.

According to another aspect of the invention, a furnace for thermaltreatment of light metal components which are continuously transportedthrough the furnace, includes a heat source, a conveyor transporting thelight metal components through the furnace in a transport direction, ablower producing an airflow circulating inside the furnace, wherein theairflow heats the light metal components inside the furnace byconvection, and partition walls arranged on the conveyor at mutualdistances between the partition walls. At least one light metalcomponent is arranged between two partition walls.

According to another aspect of the present invention, a method forthermal treatment of light metal components in a furnace, wherein thelight metal components are continuously transported through the furnace,includes placing a plurality of consecutively arranged light metalcomponents on a conveyor belt, transporting the light-metal componentsthrough the furnace, wherein an entrance opening at an entrance regionof the furnace is sealed by a light-metal component passing through theentrance opening, generating a continuously circulating warm airflow andoverflowing the light metal components in at least one temperature zoneinside the furnace with the airflow to thermally treat the light-metalcomponents, while the light metal components are continuouslytransported through the furnace, and discharging the heat-treated lightmetal components from the furnace at an exit of the furnace, wherein anexit opening at an exit region of the furnace is sealed by light metalcomponent passing through the exit opening.

According to yet another aspect of the present invention, a method ofoperating a furnace for thermal treatment of light metal components,wherein the light metal components are continuously transported throughthe furnace on a conveyor belt, includes arranging on the conveyor beltpartition walls separating mutually different temperature zones, placingat least one light-metal component on the conveyor belt between twopartition walls, and transporting the at least one light-metal componentthrough the furnace.

With the airflow circulating in the furnace, only the energy dissipatedon the plate or the component or energy occurring as lost flows needs tobe replenished, wherein the alloy components can be heated in thefurnace by convection by the airflow and a respective light metalcomponent entering the furnace and a respective light metal componentexiting the furnace can act as a barrier and prevent the airflow fromescaping from the furnace.

The furnace according to the invention uses convection for the thermaltreatment, especially for heating the light metal alloy components. Alight metal component within the context of the invention may be analready formed component, but also a component and an intermediatestage, or even a plate, which is transformed subsequent to the thermaltreatment.

Advantageously, light metal components made of an aluminum alloy, inparticular made of a wrought aluminum alloy, may be treated with thefurnace according to the invention. The respective components may beplaced on a clocked or continuously operating conveyor, and may thenenter the furnace evenly spaced in single file, and preferably atregular intervals separated by additional pressure-seal baffles. Thefurnace is thus constructed at an entrance so that a light metalcomponent entering the furnace and a light metal component exiting thefurnace operate as a barrier, so that the airflow circulating within thefurnace does not escape from the furnace. At each transition from acomponent located in the entrance region to the next component enteringthe entrance region, and likewise at the exit of the furnace, lossesoccur due to the separation between the individual components. Inaddition, overflow losses also occur at a gap between the component orbarrier and the adjacent terminations. Because a number of componentscan be transported over a short distance through the furnace either in aclocked or continuous fashion, particularly short cycle times of a fewseconds can be realized so that the furnace can effectively handle largequantities of light metal alloys for thermal treatment.

According to an advantageous feature of the present invention, thecomponents to be heated may be transported continuously, without anyinterruption. Accordingly, components may be continuously placed ontothe conveyor belt at the entrance of the furnace, transported throughthe furnace and again removed from the transporters at the exit of thefurnace.

According to another advantageous feature of the present invention, thecontinuous transport may also cooperate with upstream and downstreamproduction systems commensurate with the production cycle. For example,the conveyor belt may be briefly stopped each time a new component isadded and then possibly also when at the same time a heated component isremoved at the exit of the furnace and then restarted, until the nextcomponent.

According to another advantageous feature of the present invention, thetransport speed of the components through the furnace may not only beselected as a function of the residence time of the components insidethe furnace itself, but may also be adapted to the production processsuch that a sufficient quantity of heat-treated components is alwaysprovided for further processing.

Inside the furnace according to the invention, one or more heat sourcesmay be arranged to generate at least a predetermined temperature. Thistemperature is advantageously a temperature between 100° C. and 600° C.,which then produces with a circulation system, in particular an aircirculation system arranged inside the furnace, in conjunction with aduct system formed in the furnace, an airflow passing over the lightmetal components transported through the furnace. The heated airflowthen exchanges heat with the surface of the light metal components dueto the forced convection, thus causing heat transfer from the airflow tolight metal component. The furnace according to the invention useshereby the high thermal conductivity of aluminum in conjunction with thelarge surface area relative to the mass of the light metal component, sothat the lightweight metal component can be thermally treated, inparticular heated, within a very short time.

An exit region is then formed at the exit of the furnace, wherein thelight metal components exiting the furnace prevent the airflow fromescaping from the furnace.

Both externally heated air as well as hot gas flows may be used forconvection heating. Within the context of the present invention, theairflow may be any type of gas flow, for example also the flow of areaction gas.

Overall, the furnace according to the invention offers the advantagethat the entire system need not initially be heated at the startup ofproduction, but only the air circulated in the furnace must be temperedaccordingly. The furnace according to the invention can thus operatewith an effective efficiency and with significantly lower energy costscompared to a heating system operating using radiation or induction. Inparticular, by circulating the airflow and by preventing the airflowfrom escaping, it is possible in conjunction with a thermalencapsulation of the furnace, to only slightly reheat the heated airflowwith the heat source during circulation, thus significantly reducing theenergy cost during the operation of the furnace according to theinvention.

According to another advantageous feature of the present invention, theheat source may be designed as an electric heater and/or as a fuel-firedheater. The heat source may be arranged inside the furnace after and/orbefore the circulation system. The heated airflow or gas flowadvantageously passes directly to the light metal components, so that noflow losses occur between the airflow heated directly by the heat sourceand a long duct system. After the airflow has passed over the lightmetal components, it may enter a duct system and be once more suppliedto the circulating system, wherein it may then be reheated again to thedesired temperature shortly before or after the circulating system by aheat source disposed therein.

The choice of heat source, i.e. whether electric heater or fuel-firedheater, depends in particular on the availability of energy, the energycosts and the size of the furnace according to the invention. Forsmaller lot sizes, it may be beneficial to use an electric heater.Within the context of the present invention, however, both types ofheating systems may also be combined so that the furnace is modular andcan be used for various purposes.

According to another advantageous feature of the present invention, thecirculation systems may be arranged as a blower inside the furnace.Depending on the temperature to be generated, the blower may bearranged, for example, inside the duct system, or after the airflow haspassed over the light metal components, so that the airflow or gas flowhaving an initial temperature reaching occasionally 600° C. has cooleddown on the alloy components before passing the blowers. The blowers arethus not exposed to the maximum temperature of more than 400° C. or evenof more than 500° C., but can be operated in a flow of warm air at about100° C. to 400 C.

According to another advantageous feature of the present invention, theblowers may be used with different air blower settings, so that theairflow velocity or gas flow velocity, with which the air flows over thelight metal components, is adjustable. This allows two adjustmentparameters in conjunction with a temperature control, so that heating ofthe light metal components can be adjusted via the flow rate and/or thetemperature of the air flow.

According to another advantageous feature of the present invention, thefurnace may be thermally encapsulated, wherein sealing elements mayadvantageously be arranged at the entrance and/or exit of the furnace;the sealing elements may advantageously be formed as replaceablebaffles. The thermal encapsulation is, for example, constructed as athermally insulated jacket of the furnace, so that residual heat doesnot escape after passing the light metal components, or when passingthrough the duct system of the furnace.

Furthermore, particularly in the pulsed or continuous bulk transport oflight metal components into the furnace and out of the furnace, theentrance and the exit region, i.e. the entrance and the exit, aretherefore critical, since heat, but also the air flow, may be able toescape due to the convection principle of the furnace according to theinvention. For this purpose, the entrance and the exit may each beformed such that successive light metal components which continuouslyenter and exit the furnace seal the entrance and/or exit such that anegligible quantity of the airflow circulating within the furnaceescapes. Inevitably, hot air/gas exiting to the outside through gaps atthe entrance and exit can be collected by way of overlapping hoods andreturned to the circulation, thereby further increasing the efficiency.

By using the geometry of the components for the purpose of sealing toenhance the leak-tightness, sealing elements are formed on the entranceand/or the exit, wherein the sealing elements may advantageously beformed as a shaped baffle. When using different light metal components,especially different sized plates, the shaped baffles may be exchangedso that the cross-sectional area or the cross-frame area of the lightmetal components perpendicular to the transport direction spanning theshaped baffles may be constructed such that only a small gap is formedin a peripheral edge region. The furnace according to the invention canthus be optionally used for light metal components with differentgeometric dimensions.

According to another advantageous feature of the present invention, thefurnace may advantageously have at least two temperature zones, whereinthe light metal components may be used as a barrier between the zones,and more particularly, interchangeable shaped baffles may be located ata transition between the zones. According to another advantageousfeature of the present invention, a first temperature zone and secondtemperature zone may thus be formed in a furnace having two differenttemperature zones, so that the light metal component crossing from onezone into another zone operates as a barrier of a transition, similar asat the entrance or the exit of the furnace. Again, changeable shapedbaffles may be arranged here, so that an efficient air seal is formedbetween the zones even when the light metal components have differentgeometrical dimensions.

A mutually different thermal heat treatment may also be performed in therespective temperature zones by selecting the airflow speed and/or theair temperature. According to another advantageous feature of thepresent invention, two blowers may be arranged which generate, forexample, mutually different flow velocities in the respective zone.Moreover, two heat sources for generating different temperatures mayalso be arranged inside the furnace. Within the context of theinvention, the flow velocity within a respective zone may also beindividually adjusted on the air nozzles associated with the zones vianozzles having an adjustable cross-section, so that only one blower isused. In the context of the invention, a temperature zone may also beconfigured as a cooling zone, so that in this case an airflow which iscold compared with the airflow into heat treatment zone having atemperature of, for example, 50° C. or even only 10° C. may flow aroundthe light metal components.

Advantageously, the shaped baffles may have an opening correspondingsubstantially to a transverse frame area of the light metal componentsorthogonal to the transport direction. This ensures that even when alight metal plate is slightly slanted only small gaps are present whenthe plate passes through the shaped baffle, thereby preventing leakageof the air flow.

According to another advantageous feature of the present invention, thefurnace may have a drying zone in the region of the entrance and/or acooling zone in the region of the exit. In this way, a lubricant orother coating disposed on the light metal components can first dry inthe drying zone or be removed from the light metal components. The lightmetal components may thereafter be thermally treated in the at least onetemperature zone and then optionally cooled down again in a coolingoption located at the exit of the furnace. The components may be cooleddown to a component temperature of 100° C. or even 50° C., or also toroom temperature. In this way, for example, thermal treatment, solutionannealing, aging, or reverse annealing may be completed in a controlledmanner.

According to another advantageous feature of the present invention, thecirculating airflow inside the furnace may be passed across a surface ofthe light metal components, so that the airflow flows over the entiresurface area of the light metal components. When the air flows over thecomponents, heat is exchanged between the heated/cold air or hot gas andthe comparatively colder or warmer light metal component.Advantageously, the airflow may pass continuously across the front side,but also across the rear side of the light metal component, so that bothsides are evenly heated. The respective temperature set in the lightmetal component can then in turn be adjusted by selecting mutuallydifferent air temperatures or mutually different flow rates. Forexample, the parameters temperature and flow rate may be adjusted inonly one temperature zone, so that different components can be thermallytreated in the same furnace. When two or more temperature zones arepresent, the flow velocity and the temperature may also be adjustedindividually in each zone.

Advantageously, the light metal components may be transported throughthe furnace on a conveyor belt, in particular a chain conveyor. In thecontext of the invention, the conveyor belt, in particular the chainconveyor, includes receptacles or seats with attachments in which thelight metal components, which may be shaped as plates, can be storedwith a substantial vertical orientation. In addition, the system thenbecomes more compact, so that the airflow passes across the componentsessentially in the vertical direction from the bottom to the top or fromthe top to the bottom. The transport direction then corresponds to asubstantially horizontal direction, so that the vertically orientedcomponents assume the respective flow guiding and sealing functionbetween the zones and at the entrance and at the exit. The componentsmay be arranged at an angle.

Advantageously, the light metal components themselves may be heatedinside the furnace to a temperature between 200° C. and 450° C.Metallurgical processes then occur in the aluminum alloy used in eachcase, in particular wrought aluminum, which later produces goodformability or a corresponding homogeneous microstructure with thedesired strength properties.

The present invention also relates to a method for the thermal treatmentof light metal components in a furnace, wherein the furnace has at leastone of the aforementioned features and the method includes the followingsteps:

-   -   supplying a conveyor belt with a plurality of consecutively        arranged light metal components, in particular light metal        plates,    -   transporting the light metal components through the furnace,        wherein the entrance opening at an entrance of the furnace is        sealed by the respective light metal component passing through        the entrance opening,    -   producing a continuously circulating warm airflow and passing        the warm airflow across the light metal components in at least        one temperature zone inside the furnace, while the light metal        component is transported through the furnace in either a clocked        or a continuous fashion,    -   removing the heat-treated light metal components from the        furnace, wherein an exit opening in an exit region of the        furnace is sealed by the respective light metal component        passing through the exit opening.

With the method according to the invention, consecutively arranged lightmetal components, such as also light metal plates, may be provided on aconveyor belt and continuously moved through a furnace. A hot air or gasflow may then be generated inside the furnace using a heat source andcirculated with a blower, so that the hot air or gas flow flows acrossthe light metal components. The light metal component itself is thenheated by the forced convection on the surface of the light metalcomponent, in particular on an upper surface as well as a lower surfaceof the light metal component, whereby the light metal component, inparticular when using an aluminum alloy, can be heated in a very shorttime of sometimes only a few seconds due to its excellent thermalconductivity.

According to an advantageous feature of the present invention, therespective entrance or exit opening may be sealed by the respectivelight metal component passing through when the light metal componententers or exits the furnace, so that the air or gas flow generatedinside the furnace barely escapes to the air surrounding the furnace.According to another advantageous feature of the present invention, twoor three light metal components successively passing through theentrance opening may also assume a sealing function. The same applies tothe exit opening.

Inside the furnace itself, the heating of the light metal component maybe adjusted by selecting the flow rate of the air or gas flow and/or theair or gas temperature of the air or gas flow. Two, three or moretemperature zones may be separated inside the furnace, wherein differentheating effects can be performed on the light metal component via theparameters flow rate of the airflow or temperature of the air flow.

The heat-treated light metal components may be supplied within thecontext of the present invention to further processing, mostadvantageously with a cycle time of less than 15 seconds for eachcomponent.

According to another advantageous feature of the present invention, thefurnace may include a drying zone and a cooling zone, wherein the lightmetal components passing the drying zone are dried in the drying zone;in particular a lubricant present on the light metal components isdried. Moreover, the light metal component may be cooled in a coolingzone to a cold-hardening temperature. Advantageously, a cooling zone maybe arranged at the end of the furnace; however, one or more coolingzones may also be arranged between the individual temperature zones,allowing a heated component to be cooled and then reheated.

According to another advantageous feature of the present invention, theshaped baffles arranged in the furnace, in particular at the entranceand in the exit, but also at a transition between the zones, may beexchanged in a multi-zone furnace depending on the light metalcomponents to be treated. The shaped baffles may advantageously beselected such that a cross-sectional frame area disposed transversely tothe transport direction, in conjunction with the respective light metalcomponent passing the shaped baffle or also with two or three passinglight metal components, seals in an optimal manner, so that the airflowcannot escape.

The above-mentioned features may be combined with one another within thecontext of the invention in any manner with the associated features,without departing from the scope of the invention. The afore-describedparameters can also be applied in any way to the embodiments describedbelow.

In another embodiment, in a furnace for the thermal treatment of lightmetal components, wherein the light metal components can be transportedcontinuously through the furnace and the furnace includes a heat source,an airflow may be circulated inside the furnace, wherein the light metalcomponents can be heated inside the furnace by the airflow throughconvection and light metal components can be transported on a conveyorthrough the furnace, wherein spaced-apart partition walls are arrangedon the conveyor and at least one light metal component may be arrangedbetween two partition walls.

The aforementioned features relating, for example, to differenttemperature zones, the heat source itself, the flow velocity or theairflow temperature, but also the sealing elements in the form of shapedbaffles can be combined with this embodiment without departing from thescope of the invention. A hybrid structure, wherein the light metalcomponents are themselves arranged as a barrier in combination withpartition walls placed on the conveyor, may be constructed, whereby thepartition walls representing the larger light metal component are eachheated in the furnace, while smaller light metal components or evencomplex shaped light metal components may be arranged between thepartition walls, i.e. between the larger light metal components.

With this approach, light metal components having different dimensionsmay be placed between the two partition walls, wherein the outergeometry of the light metal components must be smaller than the outerdimensions of the partition walls, so that the partition walls assume asealing function in a continuous transport process and the light metalcomponents do not protrude over the partition walls.

Furthermore, two, three or four or more light metal components may besimultaneously arranged between two partition walls and heat-treated atthe same time, wherein the light metal components may also have complexthree-dimensional shapes.

When employing partition walls and placing at least one light metalcomponent between two respective partition walls, the furnace may beused for different production runs, without requiring retrofitting. Forexample, light metal components having mutually different outsidedimensions, particularly light metal plates, may be transported indirect succession through the furnace according to the invention,wherein in the sealing function is assumed by the partition walls andthe plates can be simply inserted in receptacles arranged between thepartition walls. In this way, the furnace according to the invention canbe flexibly utilized, without requiring set-up times for the conversionof the furnace for a new production run. This saves acquisition andmaintenance costs of the furnace according to the invention.

Furthermore, the furnace with partition walls has optionally at leasttwo mutually different temperature zones, in which the components areheated to mutually different temperatures. For example, the componentmay initially be heated step-wise and/or cooled step-wise.

According to another advantageous feature of the present invention, thepartition walls may be constructed to serve as a barrier, wherein asealing function is achieved upon passing a partition wall of anentrance and/or an exit and/or a transition, so that the airflow isprevented from escaping from the furnace; in particular, two successivepartition walls may form a continuous seal at the entrance and/or exitand/or the transition. Within the context of the invention, thetransition is located between two temperature zones, so that thecomponent transitions from one temperature zone to the other temperaturezone.

Advantageously, a seal may be formed by two consecutive partition wallswhich are arranged substantially at an angle between preferably 10° and85° with respect to the transport direction. The partition walls mayadvantageously be arranged such that, due to their angular position, theentrance and/or exit and/or the transition are substantially sealed bytwo partition walls, so that a respective airflow is prevented fromescaping from the furnace, or from passing from one temperature zoneinto the other temperature zone.

According to another advantageous feature of the present invention, thepartition walls may be arranged on the conveyor so that they can beexchanged. Within the context of the present invention, large partitionwalls of mutually different sizes may be arranged on the conveyeritself, or the distance between two partition walls may be varied. Forexample, the partition walls may be arranged on the conveyor with agreater spacing when heating two, three, four or more light metalcomponents simultaneously, whereas when heating only a singlelight-metal component disposed between the two partition walls, thepartition walls may be arranged with a mutual spacing that leaves only asmall gap between the partition wall, the component and the nextpartition wall, thus allowing the airflow to flow across the light-metalcomponent.

Within the context of the invention, the conveyor may be designed inparticular as a chain conveyor or a conveyor belt. The conveyor can thenbe operated continuously, wherein in another preferred embodiment, thepartition walls may be arranged on the chain conveyor before theentrance and be removed after the exit of the chain conveyor. In thisway, a return of the chain conveyor requires only a small footprint,which would otherwise be significantly larger due to the partition wallsprotruding from the chain conveyor. Accordingly, a much smaller returncross-sectional area is required in relation to the cross-sectional areaof the conveyor through the furnace, wherein respective partition wallsare placed on the conveyor.

Furthermore, the airflow in the furnace may advantageously be guided bythe partition walls themselves and, more particularly, two mutuallydifferent air flows in two mutually different temperature zones may beseparated by a partition wall, wherein the air flows across the surfaceof the light metal components. Within the context of the invention, arespective airflow may thus be selectively utilized in a separatetemperature zone due to the excellent thermal properties of the aluminummaterial, so that that the desired temperature of the light metalcomponent can be specifically adjusted in the temperature zone by theairflow flowing across a light metal component.

Different temperature zones may be separated from one another by thepartition walls, wherein the individual air flows are guided by thepartition walls such that they substantially do not cross over into adifferent temperature zone. Within the context of the invention, thepartition walls may advantageously be insulated, so that heat conductionfrom one temperature zone into the second temperature zone by thepartition wall itself is minimized. Furthermore, within the context ofthe invention, the partition walls may advantageously be coated, so thatthe partition walls dissipate only a small amount of thermal energy fromthe air flowing across the partition walls. Advantageously, a thermallyinsulating coating may be employed.

According to another advantageous feature of the present invention, thepartition walls may be arranged at an angle to the transport direction,for example at an angle between 10° and 80°, or between 20° and 70°, orat an angle between 30° and 60° and advantageously at an angle between40° and 50°. Arranging two successive partition walls at an angle at anentrance and/or exit and/or, a transition advantageously ensures acontinuous seal. As a second advantage, the angular arrangement alsoseparates the air flows of mutually different temperature zones fromeach other.

Another aspect of the invention relates to a method of operating afurnace, wherein the furnace has a continuous conveyor for light metalcomponents and at least two partition walls are arranged on theconveyor, wherein a respective light-metal component is positionedbetween the two partition walls and thereafter passes through thefurnace, wherein furthermore mutually different temperature zones areseparated by the partition walls. Within the context of the presentinvention, the interior of the furnace is thus sealed by the partitionwalls that continuously travel on the conveyor, wherein the light metalcomponents arranged between the partition walls are thermally treated byan airflow circulating within the furnace.

For this purpose, two consecutively arranged partition walls seal theentrance region and/or the exit region and/or a transition region,wherein the airflow circulating in the furnace, in particular theairflow circulating in the respective temperature zone of the furnace,is hindered from escaping from the furnace or from crossing into adifferent temperature zone.

According to another aspect of the present invention, the light metalcomponents can be transported continuously through the furnace and thefurnace includes a heat source, is characterized in that an airflow canbe circulated in the furnace, wherein the light metal components in thefurnace can be heated by the airflow through convection and the lightmetal components can be transported through the furnace on a conveyor,wherein an entrance and/or an exit of the furnace is sealed byrelatively movable barriers.

The relatively movable barriers are designed in particular asfast-opening and fast-closing barriers, wherein a relative movement ofthe barriers is preferably a translational movement. Consequently, alight metal component placed on the conveyor is transported toward thefurnace, with the barrier opening just before the light metal componententers the furnace, whereafter the light metal component enters thefurnace and the barrier closes again immediately after the light metalcomponent has entered the furnace. With this embodiment, light metalcomponents of different sizes can be transported through the furnace,regardless of their external dimensions.

The aforementioned features regarding the heat source, the blower andthe adjustable temperatures and the mutually different temperature zonesalso apply to the third embodiment.

According to another advantageous feature of the present invention, arelatively movable barrier may be arranged between two differenttemperature zones. It is then conceivable within the context of theinvention that three relatively movable barriers may be arranged at anentrance, in at least one transition between two different temperaturezones and at an exit of the furnace according to the present invention,which briefly open and immediately close each time a light metalcomponent passes. The barriers within the context of the presentinvention can be simultaneously controlled, wherein this embodiment isparticularly advantageous for light metal components which are arrangedon the conveyor at continuous intervals. All barriers then opensimultaneously, so that in the embodiment with three barriers, threelight metal components then enter a respective next space of thefurnace, whereafter the barriers close again. This embodiment isadvantageous, in particular, when the circulating airflow is turned offor decreased. Within the context of the invention, however, each barriercan also be operated individually, i.e. separately opened and closed.Separately opening and closing each barrier is particularly advantageouswhen light metal components are arranged discontinuously on theconveyor.

In the present invention, a relatively movable, in particularfast-opening barrier is advantageously formed as a sliding gate, whereinthe barrier may be moved up or to one side in relation to the transportdirection of the light metal components, wherein the barrier is moreoverpreferable constructed in two parts, so that each part of the barriercan be displaced to one side of the furnace. In particular, a longexcursion when opening the barrier is eliminated with a two-partembodiment of the relatively movable barrier compared to a one-partbarrier.

Even with aperture sizes of 1 m or more, by constructing the barrier intwo parts, each barrier needs to be opened and then closed again in thiscase by only 0.5 m. This shortens the opening and closing times of thebarrier especially with the two-part design.

Advantageously, an actuator is connected to the barrier for opening andclosing the barrier wherein the actuator preferably performs a linearmovement and can be driven pneumatically, hydraulically or electrically.An electromechanical actuator is also contemplated in the presentinvention. The actuator itself should be mechanically robust and have asimple design so as to be unaffected by thermal expansion caused by thethermal loads of the furnace, and an electronic control unit mayoptionally be arranged if possible in the marginal region or outside thefurnace itself, so as to prevent defects due to the thermal loads.

According to another advantageous feature of the present invention, thefurnace may be surrounded by a shell, wherein the barriers themselvesare positioned in particular inside the shell or the barriers penetratethe shell and are movable in a slot extending through the shell foropening and closing. In the first embodiment, thermal energy is hinderedfrom escaping through the slots for opening and closing the barrier inparticular with barriers arranged in a transition region from onetemperature zone into a second temperature zone located within theshell. However, this is only practical for smaller opening widths of thebarriers in order to keep the outer dimensions of the shell also small.However, when an opening of the barrier of 1 m or more is necessary, itis advantageous within the context of the present invention, when thebarriers can be moved through a respective slot of the shell. Thebarriers then leave at least partially the interior of the furnace uponopening and return into the furnace upon closing.

According to another advantageous feature of the present invention, heatloss through the slot may be reduced by providing thermal insulationmeasures in the slot region. For example, this may be a thermal seal. Inanother advantageous embodiment, the partition walls may themselves becoated and/or thermally insulated. In this way, the barrier itself can,on one hand, keep the heat input caused by the airflow flowing acrossthe barrier small and, on the other hand, prevent the heat from exitingthrough the barrier by way of heat conduction at the entrance and/orexit, as well as prevent—by way of a thermally insulated barrier—heattransfer by thermal conduction from one temperature zone to the nexttemperature zone having a different temperature.

The invention also relates to a method for operating the furnace withrelatively movable barriers, wherein a light metal component is placedon the conveyor and the light metal component is transported into thefurnace, wherein the barrier is opened at the entrance of the furnacejust before the light metal component enters the furnace and is closedagain immediately after the lightweight metal component has entered thefurnace and/or wherein the barrier at the exit of the furnace is openedjust before the light metal component exits from the furnace and isclosed again immediately after the light metal component has exited fromthe furnace.

Airflow recirculated within the furnace may advantageous be stopped orreduced when a barrier is opened, and may be restarted or increasedafter the barrier is closed. This ensures that the amount of heatescaping the furnace or the heat transfer between the mutually differenttemperature zones is reduced to a minimum when the barrier is opened orclosed. The energy costs of operating the system are thereby reduced.

Moreover, within the context of the present invention two or more lightmetal components may pass the barrier when a barrier is opened, and whenthe barrier is closed again after the light metal components have passedthe barrier. In this way, the furnace according to the invention and themethod of operating the furnace can be flexibly used so that differentproduction lines of metal components to be heated can be thermallytreated with the furnace without long setup times. For example, lightmetal components having different external geometric dimensions, in theform of plates or even complex-shaped three-dimensional metal componentsmay be simultaneously thermally treated in the same furnace withoutrequiring a reconfiguration or modification of the furnace.

Within the context of the invention, the relatively movable barriers mayadvantageously be opened by a control system only as wide as necessaryto create a sufficiently large unobstructed opening sufficiently forpassage of the component according to its external geometric dimensions.The barrier(s) is/are then closed again after the component has passed.Thus, for example, an opening slightly larger than that 1 m² may beprovided for a large plate of 1 m². For a plate having an area of only ¼m², the barrier may be opened only so far as to provide an openingslightly larger than ¼ m², so that the plate can pass through theopening, whereafter the barrier is again closed.

Within the context of the invention, a barrier that opens in threedirections may be selected, wherein the barrier is formed by twobarriers moving toward each side of the conveyor and a barrier that ismovable vertically upward relative to the conveyor, so that therespective unobstructed areas can be individually adjusted. Thisminimizes the energy exiting via the slots when the components pass intothe furnace.

According to another advantageous feature of the present invention, thelight metal components may be arranged an angle to the transportdirection, in particular at an angle between 30° and 90°, allowing manycomponents are to be transported successively and continuously throughthe furnace, wherein the furnace has longitudinal outside dimensions ofmaximally several meters, instead of several dozen or even severalhundred meters which would otherwise be required when plates are placedon the conveyor horizontally, i.e. plates or light metal componentshaving a lengthwise extension in the transport direction. The airflowcan then be circulated within the furnace according to the inventionfrom the bottom to the top or from the top to the bottom and flowsacross the plates arranged on the conveyor at an angle to the transportdirection and optionally across the partition walls arranged in between.In summary, a universally usable furnace having compact overalldimensions for the heat treatment of light metal components with variousgeometrical dimensions can hereby be provided.

BRIEF DESCRIPTION OF THE DRAWING

Other features and advantages of the present invention will be morereadily apparent upon reading the following description of currentlypreferred exemplified embodiments of the invention with reference to theaccompanying drawing, in which:

FIG. 1 shows the furnace according to the present invention in a sideview;

FIG. 2 shows a shaped baffle according to the invention in a plan view;

FIG. 3 shows an end view of the entrance region of a furnace;

FIG. 4 shows an end view with different sized plates;

FIG. 5 shows a cross-sectional view through the furnace system withchain conveyor and heat source;

FIG. 6 shows a furnace according to the invention in a side view withrevolving partition walls;

FIG. 7 shows a furnace according to the invention with revolvingpartition walls;

FIG. 8 shows a furnace according to the invention with relativelymovable barriers;

FIG. 9 shows a furnace according to the invention in a plan view withrelatively movable barriers, and

FIGS. 10 a and b shows relatively movable barriers in a furnaceaccording to the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Throughout all the figures, same or corresponding elements may generallybe indicated by same reference numerals. These depicted embodiments areto be understood as illustrative of the invention and not as limiting inany way. It should also be understood that the figures are notnecessarily to scale and that the embodiments are sometimes illustratedby graphic symbols, phantom lines, diagrammatic representations andfragmentary views. In certain instances, details which are not necessaryfor an understanding of the present invention or which render otherdetails difficult to perceive may have been omitted.

Turning now to the drawing, and in particular to FIG. 1, there is showna furnace 1 according to the invention for thermal treatment of lightmetal components 2 in the form of plates. Light metal components 2 areplaced on a conveyor belt 3 and transported in the transport direction 4into the furnace 1. For this purpose, the furnace 1 has an entrance E,through which the light metal components 2 enter the furnace 1. The sameapplies for the exit A, wherein the furnace 1 has an exit A.

Within the furnace 1, the light metal component 2 first comes intocontact with a drying zone T in which the light metal component 2 isdried to remove a possible lubricant. An airflow L circulates within thedrying zone T, which flows around both a front side 5 and a back side 6of the light metal component 2. The light metal component 2 transitionsfrom the drying zone T into a first temperature zone Z1, in which againan airflow L1 flows around the front side 5 and the back side 6 of thelight metal component 2. The airflow L1 flowing around the light metalcomponent 2 in the first temperature zone Z1 has hereby a flow velocityv1 and a temperature T1, thus subjecting the light metal component 2 toa predetermined component temperature within the temperature zone Z1.

Subsequently, the light-metal component 2 enters a second temperaturezone Z2, in which again an airflow L2 flows across a front side 5 and aback side 6, wherein the airflow L2 of the second temperature zone Z2has a second flow velocity v2 and a second temperature T2. In this way,a component temperature of the light metal component 2 is adjusted whenpassing through the second temperature zone T2.

After the second temperature zone T2, the light metal component 2 entersa cooling zone Z3, wherein in the cooling zone Z3 an airflow L3 againflows across the front side 5 and the rear side 6 of the light-metalcomponent 2, which has a third flow velocity v3 and a third temperatureT3, wherein in particular the temperature T3 is lower than thetemperature T1 and T2, and the flow velocity v3 is higher than the flowvelocities v1 and v2. The component is thereby cooled in the illustratedembodiment in the cooling zone Z3 to a cooling temperature. Thecomponent then exits from the furnace 1 at an exit A and is removed, andthen supplied as heat-treated component 7 to additional unillustratedtreatment processes.

The individual air flows L can be produced with an unillustrated blower,and the flow speed v1, v2, v3 can then be adapted to the respective zoneby varying a cross-section or by using a valve. Within the context ofthe present invention, however, each zone may have a separate blower.The same applies to the temperature. The air may be heated by one ormore heat sources, for example, a separate heat source may be associatedwith each temperature zone Z1, Z2.

In the embodiment shown in FIG. 1, the light metal components 2 in theform of plates are arranged between insertion devices 8 so that they aretransported through the furnace 1 in the transport direction 4 with anessentially vertical orientation. However, within the context of theinvention, as shown in FIG. 2, the plates may also be transportedthrough the furnace substantially at an angle α. Shaped baffles 9 arearranged at both the entrance E and the exit A, as well as between theindividual zones, wherein the shaped baffles 9 are illustrated in moredetail in FIG. 3.

FIG. 3 shows a shaped baffle 9 according to the invention in a planview. The light metal component 2 passes the shaped baffle 9 in thetransport direction 4, i.e. towards the image plane, wherein a gap 12remains between the outer edge 10 of the light metal component 2 and theopening 11; this gap 12 needs to be minimized, so as to minimize theairflow L that can escape through the gap 12 from the temperature zonesZ1, Z2, or from the entrance A or exit E of the furnace 1.

The light metal component 2 according to FIG. 3 has an asymmetricconfiguration; however, large and small rectangular plates can also beguided through the furnace 1 by exchanging the shaped baffles 9. This isillustrated in FIG. 4, in which a small light metal component 2 iscaptured by the shaped baffle 9 and, as indicated by the dotted line, alight metal component 2 with larger geometric dimensions can betransported through the furnace 1 by exchanging the shaped baffle 9,wherein a small gap 12 remains between the light metal component 2 andthe shaped baffle 9.

Furthermore, FIG. 5 shows a cross-sectional view through the furnace 1according to the invention, wherein the light metal component 2 istransported through the furnace 1 in the transport direction 4, whereinthe cross-sectional view shows a plan view on the shaped baffle 9. Ancross section through the temperature zone Z1 is shown as an example. Ablower 13 generating the air circulation within the temperature zone Z1is located in the lower part of the furnace 1. The airflow L circulatedby the blower 13 passes through a heat register 14 where it is heatedand then flows across the light metal component 2. The airflow L iscollected in an upper region and return to the blower 13. Alsoillustrated here are additional heating devices 15, with which theairflow L can be additionally or exclusively heated, so that the heatsource is located upstream, and not like the heat register 14 downstreamof the blower 13.

FIG. 6 shows a second embodiment of a furnace 1 according to theinvention, wherein the furnace 1 has once more a conveyor 4 in the formof a conveyor belt 3, which transports light metal components 2 in theform of plates 2, 2 a, 2 b, 2 c in the transport direction 4 through thefurnace 1. For this purpose, the light metal components 2 are placed onthe conveyor belt 3 and enter the furnace 1 through an entrance E in thetransport direction 4. Partition walls 16 are arranged on the conveyorbelt 3 at regular intervals a, wherein two light metal components 2 areeach arranged here between two respective partition walls 16. Thefurnace 1 shown in FIG. 6 includes a drying zone T and a firsttemperature zone Z1 and a second temperature zone Z2, wherein througheach of the drying zone and the temperature zones Z1, Z2 respectively,corresponding airflow L, L1, L2 flows across the front side 5 and theback side 6 of the light metal components 2.

A significant advantage of the present second embodiment according toFIG. 6 is that even light metal components 2 having geometries differentfrom the plates 2, 2 a, 2 b, 2 c can be transported through the furnace1. For example, plates 2 a longer than the light metal components 2 canbe transported through the furnace 1. Moreover, corrugated or groovedplates 2 b as well as three-dimensionally shaped components 2 c can betransported through the furnace. The partition walls 16 each provide aseal at an entrance E and exit A, as well as between the temperaturezones T, Z1, Z2.

FIG. 7 shows a similar embodiment as FIG. 6, wherein only one lightmetal component 2, 2 b, 2 c is located here between the partition walls16. Within the context of the invention, the distances a, a1, a2 betweenthe individual partition walls 16 may be varied, with a≠a1≠a2. Thepartition walls 16 shown in FIG. 6 and FIG. 7 can preferably be placedon the conveyor belt 3 before the entrance E into the furnace 1 andremoved from the conveyor belt 3 after the exit A of the furnace 1. Thereturn 17 of the conveyor belt 3 then needs to have only a smallinstallation height h.

FIG. 8 shows a third embodiment of the furnace 1 according to theinvention, wherein relatively movable barrier 18 are placed at theentrance E and at the exit A and also at the transitions Ü between theindividual temperature zones T, Z1, Z2. The barriers 18 can then performa relative movement R in order to enable the light metal components 2positioned on the conveyor belt 3 to be transported in a transportdirection 4. The relatively movable barriers 18 of the present inventionalso allow thermal treatment of components or plates 2, 2 a, 2 b havingdifferent lengths, for example longer plates 2 a as well as corrugatedcomponents 2 b, in a the same furnace 1.

In the embodiment shown in FIG. 8, the plates 2 a, 2 b are disposed onrespective insertion devices 8 substantially at a 90° angle relative tothe transport direction 4 on the conveyor belt 3. However, the plates 2a, 2 b, may also be arranged at an angle α on the conveyor belt 3, asshown in FIG. 2, 6 or 7. For this purpose, unillustrated insertiondevices 8 or any other positioning means for insertion on the conveyorbelt 3, for example a chain conveyor, are arranged on the conveyor belt3 or on the components or plates themselves. The respective relativelymovable barriers 18 are, as shown in FIG. 8, constructed for upward orrelative movement with respect to the transport direction 4 and thefurnace 1.

FIG. 9 shows another embodiment of relatively movable barriers 19 a, 19b, wherein the barriers 19 a, 19 b are here constructed in two parts andalso arranged relatively movable relative in the furnace 1. The two-partbarrier 19 a, 19 b thereby performs with one part 19 a a relativemovement R to one side and with the second part 19 b a relative movementR to the opposite side. The view shown in FIG. 9 on an inventive furnace1 from above thus allows the light metal components 2 to pass in thetransport direction 4 by opening the barriers 19 a, 19 b. The furnace 1has here also two different temperature zones Z1, Z2, wherein anunillustrated airflow can be circulated in each of the zones Z1, Z2 andthe light metal components 2 transported through the furnace 1 can bethermally treated by convection. Furthermore, the furnace 1 shown inFIG. 9 includes a shell 20 surrounding the entire furnace 1, wherein thebarriers 19 a, 19 b are relatively movable inside the shell 20. The endface of the split barrier 19 a, 19 b is shown in the detailed view ofFIG. 9, wherein different types of sealing labyrinths 21 can be formedwhich prevent the circulated airflow L1, L2, L3 and/or the heat fromcrossing over between the two different temperature zones Z1, Z2, Z3 orprevent heat from escaping from the entrance E or exit A. For example,the labyrinth seals may have a U-shaped or C-shaped cross-section.

FIGS. 10 a and 10 b show another embodiment of the relatively movablebarriers 18, wherein the barriers 18 perform hereby the relativemovement R by way of a slot 22 disposed in the shell 20. FIG. 10 b showsthe barrier 18 coupled with an actuator 23 which performs the relativemovement R as a linear movement, wherein only a single coupling rod 24is guided through the slot 22 in the shell 20, thereby preventingpossible leakage of airflow L1, L2, L3 and/or heat from the interior ofthe furnace space.

While the invention has been illustrated and described in connectionwith currently preferred embodiments shown and described in detail, itis not intended to be limited to the details shown since variousmodifications and structural changes may be made without departing inany way from the spirit and scope of the present invention. Theembodiments were chosen and described in order to explain the principlesof the invention and practical application to thereby enable a personskilled in the art to best utilize the invention and various embodimentswith various modifications as are suited to the particular usecontemplated.

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims and includes equivalents of the elements recited therein:
 1. A furnace for thermal treatment of light metal components which are continuously transported through the furnace, the furnace comprising: a heat source, a conveyor transporting the light metal components through the furnace in a transport direction, and a blower producing an airflow circulating inside the furnace, wherein the airflow heats the light metal components inside the furnace by convection, and a light metal component entering the furnace and a light metal component exiting from the furnace are constructed as a barrier so as to hinder the airflow from escaping from the furnace.
 2. The furnace of claim 1, wherein the heat source is constructed as at least one of an electric heater and a fuel-fired heater.
 3. The furnace of claim 1, wherein the blower is arranged inside the furnace.
 4. The furnace of claim 1, wherein the furnace comprises sealing elements arranged at an entrance or exit of the furnace proving a thermal seal.
 5. The furnace of claim 4, wherein the sealing elements are constructed as exchangeable shaped baffles.
 6. The furnace of claim 1, wherein the furnace comprises at least two temperature zones, with the light metal components providing a barrier between the at least two temperature zones.
 7. The furnace of claim 6, wherein exchangeable shaped baffles are disposed at a respective transition between the at least two temperature zones.
 8. The furnace of claim 7, wherein the shaped baffles have an opening that corresponds substantially to a transverse cross-sectional frame area of the light metal components orthogonal to the transport direction.
 9. The furnace of claim 1, wherein the furnace comprises a drying zone disposed in a region of an entrance of the furnace.
 10. The furnace of claim 1, wherein the furnace comprises a cooling zone disposed in a region of an exit of the furnace.
 11. The furnace of claim 1, wherein the circulating airflow flows across a surface of the light metal components when passing through the furnace.
 12. The furnace of claim 6, wherein the circulating airflow flows across a surface of the light metal components in the at least two temperature zones with at least one of mutually different air temperatures and mutually different flow velocities.
 13. The furnace of claim 1, wherein the conveyor belt is a chain conveyor.
 14. The furnace of claim 1, wherein the light metal components are heated to a temperature between 200° C. and 450° C.
 15. A method for thermal treatment of light metal components in a furnace, wherein the light metal components are continuously transported through the furnace, the method comprising: placing a plurality of consecutively arranged light metal components on a conveyor belt, transporting the light-metal components through the furnace, wherein an entrance opening at an entrance region of the furnace is sealed by a light-metal component passing through the entrance opening, generating a continuously circulating warm airflow and overflowing the light metal components in at least one temperature zone inside the furnace with the airflow to thermally treat the light-metal components, while the light metal components are continuously transported through the furnace, and discharging the heat-treated light metal components from the furnace at an exit of the furnace, wherein an exit opening at an exit region of the furnace is sealed by light metal component passing through the exit opening.
 16. The method of claim 15, further comprising selecting at least one of a flow rate of the airflow and an air temperature in the at least one temperature zone for heating the light metal components.
 17. The method of claim 15, further comprising transferring the light metal components to an additional treatment process in a cycle time of less than 15 seconds.
 18. The method of claim 15, wherein the light metal components are dried in the drying zone to remove a lubricant.
 19. The method of claim 15, wherein the light metal components are cooled in a cooling zone to an age-hardening temperature.
 20. The method of claim 15, wherein shaped baffles are exchanged in dependence of the light metal components to be treated.
 21. A furnace for thermal treatment of light metal components which are continuously transported through the furnace, the furnace comprising: a heat source, a conveyor transporting the light metal components through the furnace in a transport direction, a blower producing an airflow circulating inside the furnace, wherein the airflow heats the light metal components inside the furnace by convection, and partition walls arranged on the conveyor at mutual distances between the partition walls, wherein at least one light metal component is arranged between two partition walls.
 22. The furnace of claim 22, wherein at least two temperature zones having mutually different temperatures are formed inside the furnace.
 23. The furnace of claim 22, wherein the partition walls are constructed as a barrier to prevent the airflow from escaping from the furnace when a partition wall passes at least one of an entrance, an exit and a transition between the at least two temperature zones.
 24. The furnace of claim 23, wherein two successive partition walls produce a continuous seal at at least one of the entrance, the exit and the transition.
 25. The furnace of claim 21, wherein two or more light metal components are arranged between two partition walls.
 26. The furnace of claim 21, wherein the partition walls on the conveyor are exchangeable.
 27. The furnace of claim 21, wherein the conveyor is a chain conveyor or a conveyor belt.
 28. The furnace of claim 27, wherein the partition walls are configured for placement on the chain conveyor before an entrance of the furnace and for removal from the chain conveyor after an exit of the furnace.
 29. The furnace of claim 21, wherein the airflow is guided by the partition walls and flows across a surface of the light metal components.
 30. The furnace of claim 22, wherein a partition wall separates two different air flows in two different temperature zones.
 31. The furnace of claim 21, wherein the partition walls are arranged on the conveyor at an angle between 10 degrees and 80 degrees.
 32. The furnace of claim 21, wherein the partition walls are arranged on the conveyor at an angle between 20 and 70 degrees.
 33. The furnace of claim 21, wherein the partition walls are arranged on the conveyor at an angle between 30 and 60 degrees.
 34. The furnace of claim 21, wherein the partition walls are arranged on the conveyor at an angle between 40 and 50 degrees.
 35. A method of operating a furnace for thermal treatment of light metal components, wherein the light metal components are continuously transported through the furnace on a conveyor belt, the method comprising: arranging on the conveyor belt partition walls separating mutually different temperature zones, placing at least one light-metal component on the conveyor belt between two partition walls, and transporting the at least one light-metal component through the furnace.
 36. The method of claim 35, wherein two consecutively arranged partition walls seal at least one of an entrance region, an exit region and a transition region separating the different temperature zones, thereby hindering an airflow circulating in the furnace from escaping from the furnace or crossing over between the different temperature zones. 